A good rule of thumb is that if the plant blooms on new growth, it can be pruned in winter, before the new season's growth begins and after the final bloom of the year. Be careful with spring-blooming shrubs—those usually can't be pruned in winter without damaging the flower buds and ruining the blooming season.
However, there are cultivated plants which are more susceptible to problems if the old foliage and dying stems are left to rot. Diseases can overwinter in dead foliage, as can slugs and other pests. Old stems can also get battered about by fall and winter winds, which will damage the plant's crown and roots.
Q: When is the best time to cut back in the fall? A: “When they start to look too ratty for you and before the fresh new growth begins,” says Sarah. For plants that are frost-sensitive, wait until after the plants have gone through several hard frosts to ensure they're dormant before cutting back.
The 1/3 rule involves cutting about 1/3 of wood during any pruning activity. This moderate pruning practice is a balanced approach to thinning out shrubs to stimulate new growth. The plant loses a good amount of stems, usually on the top section, allowing more light and air to enter the inside of the plant.
To prevent the disease from returning the following year, we suggest cutting the plants back in the fall and removing any debris – no matter the variety! It will give your plants a clean start next season. *Destroy any foliage with symptoms of powdery mildew and disinfect pruners before trimming other plants.
But when should hostas be cut back? Hostas should be cut back in late fall. Healthy hosta leaves can be left on the plant in early fall to capture much-needed energy, but all leaves should be trimmed off after the first frost to deter slugs and other pests from making your hosta their winter home.
The process of trimming back plants is the same for nearly all perennials. Begin by cutting the plant back to 3 to 5 inches above the soil line. Using a sharp pair of pruners or hedge trimmers, cut off all of the foliage and stems. Cut the plants down to within three to five inches of the soil line.
The good news is that hostas, also known as plantain lilies, are tough and forgiving plants. Even if you forget to prune them at a certain time or you neglect to prune them at all, they'll still survive just fine, even if they don't look their best.
Some plants can overwinter as houseplants. The most successful are: geraniums, Boston ferns, and tropical plants such as begonia, caladium, coleus, and hibiscus. For these plants, the general rule is to give them as much light and humidity as possible; keep away from heat ducts. Some will benefit from artificial light.
After “how?", the second most-asked question we get about pruning is “when?” (Or, "Can I prune this now?") The rule of thumb is to prune immediately after bloom for flowering shrubs, in late winter or early spring for non-blooming shrubs (particularly for heavy pruning), and not after mid-August for any shrubs.
If low temperatures loom, cover plants with cloth, burlap or plastic at night. If you use plastic, be sure to remove the covering during the day since temperatures can heat up, causing premature bud growth. Also, when covering, avoid damaging the top part of the plants.
Bury the pots or bring them inside.
Simply dig a hole and plant the perennial pot and all. This way the soil in the pot will benefit from the temperature-stabilizing mass of the ground soil. Alternatively, bring the pot into an unheated, not-too-bright interior space, such as a garage or cold cellar.
Deep water plants before ground freeze, and continue to water during winter months when temperatures remain above freezing but without precipitation, Erect physical windbreaks. Wrap problem plants with burlap or other material to protect from wind and subsequent moisture loss to evergreen shrubs and small trees.
The best rule of thumb to use when making pruning decisions is to know that you can safely remove up to one-third of the plant's growth at any one time.
RULE 1: Prune your block with the weakest trees first and your strongest trees last. Trees that are pruned in early winter become more vigorous than trees that have been pruned just before or after flowering.
Older trees and shrubs especially benefit greatly from pruning, as it will encourage them to produce new, vigorous growth that results in similarly healthy flowers and fruit. Younger woody plants should be pruned in a way that encourages them to produce a balanced, open structure of stems or branches.
If you want to prune in fall, wait until trees drop their leaves and are dormant—usually October or November.
It's important to cut back foliage in the fall to protect flowering plants from disease and give them a clean start for regrowth as winter starts to turn into spring. However, there are some plants you can keep around through the winter since they benefit wildlife and still offer visual interest for your home.